Binary package “python3-gi” in ubuntu xenial

Python 3 bindings for gobject-introspection libraries

GObject is an abstraction layer that allows programming with an object
paradigm that is compatible with many languages. It is a part of Glib,
the core library used to build GTK+ and GNOME.
.
This package contains the Python 3 binding generator for libraries that
support gobject-introspection, i. e. which ship a gir1.2-<name>-<version>
package. With these packages, the libraries can be used from Python 3.